Multi-Input Multi-Output (MIMO) systems for optical communications

Multiple Input Multiple Output (MIMO) Radio Frequency (RF) systems can offer substantial increases in capacity over their single antenna wireless link counterparts. The aim of this work is to investigate the benefits that MIMO may have in free space optical systems. To this end we have investigated

  

  • MIMO in Line of sight systems. Here an architecture that uses arrays of white LEDs that can provide high data rate communications to a receiver that uses an array of photodetectors has been developed. In this case MIMO allows the low bandwidth LED transmitters to be used in parallel and the crosstalk between channels to be compensated. A system based on white LEDs and also one using infra-red sources has been demonstrated
  • MIMO in non-Line of sight systems. Experiments show that it is possible to used MIMO techniques for data transmission in such situations

 

This work is in its preliminary stages and we are working to understand how best to use this extra 'degree of freedom' to increase the capacity of optical wireless systems.